1. Field of Invention
This invention relates to a filter for use on a storm sewer catch basin equipped with a top grate. The ground water flows through the filter into the grate and catch basin, and then out the sewer line. Before the ground water flows into the sewer line solid pollutants need to be filtered out of the storm water.
2. Description of the Prior Art
Most catch basin filtration systems are not immediately upstream from drain grates or are not designed for a catch basin with only a grate inlet cover. In the past, filtration has been accomplished using devices which were downstream and below the grate. Most are labor intensive being constructed on site. Caldwell (U.S. Pat. No. 1,310,055) shows a device that strains out only large debris such as sticks and leaves. The modern regulations require that smaller solids such as sand or silt are also removed from storm water.
Chinn, et. al. (U.S. Pat. No. 5,632,888) and McDermott (U.S. Pat. No. 6,045,691) developed a filter upstream from a catch basin chamber but they are designed for curb inlets only and not for a catch basin top with a grate covering. Allen, et al (U.S. Pat. No. 6,015,489), Sharpless (U.S. Pat. No. 5,849,198), Bennett (U.S. Pat. No. 6,096,200), Logue (U.S. Pat. No. 5,575,925) and Logue (U.S. Pat. No. 5,372,714), all develop filtration systems which position the filter apparatus down stream from the inlet opening grate. These are labor intensive to install and maintain.
Strawser Sr. (U.S. Pat. No. 5,954,952) develops a filtration system for catch basins with a curb inlet combined with a gutter inlet. This does not refer to only a grate inlet as in our invention.
Faneli (U.S. Pat. No. 5,733,445) shows an apparatus shows a thin support grate on top of an inlet grate. The support grate is fabricated from metallic material such as steel. This is expensive to manufacture and no overflow by pass is included. Best management practices in OregonDepartment of Transportation BMP Manual, xe2x80x9cHydraulics Manual Volume 2,xe2x80x9d printed December 1999 pages 3-78 to 3-83 include inlet protection filtration systems which are upstream from a catch basin grate. All such included systems are devices to be constructed on site. A filtration system on top of a grate is shown on page 3-78. This shows a need for such a filter. These on-site fabrications are labor intensive and of inconsistent quality. As described, they are a traffic hazard when placed in a street and have no overflow provision for high flow conditions.
There is a need for a prefabricated filter with a bypass which mounts on the top of a catch Basin. No catch basin filtration systems which essentially rests on top of the grate includes an overflow by pass which is also safe for traffic. For the foregoing reasons there is need for such a storm water catch basin filter.
Our invention is a removable catch basin filter for a storm sewer catch basin which is equipped with a removable top inlet grate. The filter is essentially located on top of the catch basin grate. The filter is typically composed of a porous geo textile fabric which covers the grate inlet. Pollutant solids are held back by the fabric while the water flows into catch basin through the grate. The filter enwraps the grate thereby preventing storm water from entering the grate without passing through the filter. The filter includes a centrally located by pass opening. A wall water barrier protects the opening and, during low flows, forces the water to enter the grate only through the surrounding filtration fabric. The wall is limited in height. During high water conditions the water flows over this low wall and into the catch basin. This wall is made of a compressible material such as foam rubber and easily flattens with traffic weight. The filter therefore poses little threat to traffic safety. The wall springs the by pass opening top back to its former position when it is no longer weighed down.